Rambo? No need to feel that way because you are using a particular size of tool. The important thing is having it, that it's sharp, and knowing how to use it. Titanium is 30% stronger than steel and 30% lighter. If you'll check
www.knifeforums.com, you should find some useful info there, or somebody who can help you. It seems the most experienced divers, like SeaRat on this forum, have found a large and small knife and shears to be the way to go.
What people think of your appearance isn't worth wasting one second on. If that's their first concern, I'd keep well away from them myself, unless they know how to breathe water after their air has run out.
Why not always have them with you? I wonder how many people have scoffed at the notion they need two knives, carried not even one, and then died regretting it? If two blades are good for the SEAL's, they're good enough for me, (and the shears too). Now, keep your wits about you, and go have fun!
an old River Rat